The invention relates to a cigarette paper and a cigarette for reducing the amount of unwanted byproducts in mainstream smoke during smoking of the cigarette, as compared to a conventional cigarette. More particularly, the invention relates to a cigarette paper having heat-degradable filler particles, and a cigarette comprising a cigarette paper wrapper having heat-degradable filler particles. The heat-degradable filler particles are capable of being dissipated during smoking of the cigarette to increase the porosity in an annular zone of the cigarette paper.
Various cigarette designs for reducing the amounts of unwanted byproducts and/or lowering the combustion temperature of a cigarette during smoking of the cigarette have been described in the art. A variety of unwanted byproducts may be contained in cigarette smoke, such as polynuclear aromatic hydrocarbons (PAHs), various heterocyclic compounds, hydrogen cyanide (HCN), nitric oxides (NOx), carbon monoxide (CO), and other components of tar. Generally, higher combustion temperatures promote formation of these unwanted byproducts. Techniques known in the art, such as normal dilution, filtration, or selective filtration are not completely satisfactory for reducing unwanted byproducts in mainstream smoke.
For example, cigarettes having perforations in the wrapper for increasing air dilution have been described. U.S. Pat. No. 5,062,434 discloses a cigarette paper with a plurality of rows of perforations and U.S. Pat. No. 4,865,055 relates to a ventilated cigarette of uniform flavor. Additionally, U.S. Pat. No. 5,178,166 relates to a filter cigarette with a filter portion comprising a fluted tubular extrusion, as well as a porous wrapper comprising a longitudinal band of perforations to dilute the mainstream cigarette smoke with outside air. Another strategy for diluting the mainstream cigarette smoke is described in U.S. Pat. No. 4,548,677, which relates to a cigarette paper having a pore structure which is said to greatly promote diffusion, especially of carbon monoxide. However, one of the problems with perforated cigarettes is a lack of control over the level of air dilution, which can lead to a cigarette that may be considered tasteless and/or unsatisfactory to a smoker.
For better control over air dilution, cigarettes having perforations filled with a material that melts or sublimes during smoking of the cigarette have been described in the patent literature. For instance, U.S. Pat. No. 2,992,647 discloses a thermostatically controlled cigarette, having openings that have been filled with a material of low melting or vaporizing point that will melt or sublime as the cigarette is smoked, thus opening up the holes some distance in advance of the charline. The materials used to fill the holes in the ""647 Patent include polyethylene, cellulose, monosodium phosphate, and menthol. Similarly, U.S. Pat. No. 3,511,247 discusses a smoking product with ventilation holes adapted to open during smoking to provide smoke diluted by air. The holes or perforations in the wrapper may be filled or covered with a substance (e.g. cellular materials such as ethyl cellulose) that is disintegrated by the heat generated by the burning of the tobacco in the cigarette. Also, U.S. Pat. No. 3,473,535 discloses a cigarette with holes that are sealed with a fusible material, and which open up about 1 cm behind the burning zone. Examples of fusible materials include waxes, such as paraffin, tallow, or stearin.
Various materials have been disclosed for filling perforations in the cigarette wrapper. For example, U.S. Pat. No. 3,699,973 discloses a film covering for a smoking product wrapper with apertures, which is either porous or deliberately perforated with vents or apertures. The openings or vents are covered with a polymeric film that has been treated using processes such as degradation, to expedite the removal of film over the apertures by smoke components, so that air is permitted to dilute the smoke during the latter stages of smoking. In another example, U.S. Pat. No. 4,784,164 relates to tobacco rod wrappers and compositions for their production. The wrappers have porosity apertures which are partially or fully blocked by a coating of a heat-removable, porosity-reducing composition. The heat-removable, porosity-reducing composition comprises materials such as palmitates, which melt as the burning tip of the smoking rod approaches, thus increasing the porosity of the wrapper. However, an overall disadvantage to all of these techniques is that creating and filling the perforations typically require additional manufacturing steps and/or special equipment.
Another approach for effecting air dilution of mainstream smoke is described in U.S. Pat. No. 2,754,828, which discloses a cigarette having a form-retaining non-combustible wrapper adapted to hold the ash as the cigarette is smoked. The wrapper has apertures that permit air to enter in order to support the burning of the tobacco and to provide ventilation to cool the hot gases or air before being drawn into the mouth of the smoker. The apertures are filled with a readily combustible material, such as cellulose fibers, which permits the wrapper to become porous or apertured by the heat generated during the burning of the tobacco.
Yet another strategy for promoting air dilution of mainstream smoke has been to treat the cigarette paper wrapper with burn control agents. For instance, U.S. Pat. No. 3,667,479 and U.S. Pat. No. 3,699,972 disclose a cigarette with a modified paper wrapper. The wrapper is treated in pre-selected areas with a burn control additive or a burn accelerating agent over a pre-selected area of the cigarette paper wrapper. When the burning coal reaches the area of treatment during smoking of the cigarette, the treated area is burned away, creating an aperture and allowing the passage of air.
Another method for treating the cigarette wrapper is discussed in U.S. Pat. No. 4,590,955. The ""955 Patent describes adding a non-ionic surfactant to the cigarette paper wrapper, which is said to reduce the amount of carbon monoxide produced upon burning the wrapper during smoking.
Other approaches to reduce the amount of unwanted byproducts in cigarette smoke include various filtering techniques. For example, U.S. Pat. No. 3,828,801 relates to a filter for removing polynuclear aromatic hydrocarbons from tobacco smoke using polysiloxane compositions located in the filter section of a tobacco smoking device in admixture with an endothermically dissociable hydrate or carbonate filler. In another example, U.S. Pat. No. 5,909,736 describes methods for removal of unwanted compounds from cigarette smoke using biological substances, such as metal ions (Fe+2, Cu+2, Mg+2) complexed with porphirin rings, as well as Fe+2 ions sterospecifically bound to protein molecules.
Despite all of the developments in the art to date, there remain various disadvantages to each of the above techniques. For instance, many of these techniques require additional manufacturing steps, as well as special equipment for processing the cigarette paper wrapper or the cigarette, which may lead to additional expense and/or slower cigarette production. Thus, an economical manufacturing technique for making cigarettes designed to reduce unwanted byproducts and/or lowering the combustion temperature in a cigarette would be advantageous. Preferably, such a cigarette would not require additional processing steps for perforating the cigarette or cigarette paper, or filling the perforations.
The invention relates to a cigarette paper having heat-degradable filler particles, as well as a cigarette comprising a cigarette paper wrapper having heat-degradable filler particles. The heat-degradable filler particles are capable of being dissipated during smoking of the cigarette to increase the porosity of the cigarette paper wrapper.
In a preferred embodiment of the invention, the heat-degradable filler particles are dissipated during smoking of the cigarette to increase the porosity of the cigarette paper wrapper to a final porosity from about 30% to about 60%. In yet another preferred embodiment, the invention produces a cigarette with the air dilution from about 30 percent to about 90 percent. Preferably, the combustion temperature in a cigarette according to the invention, is maintained at or near the smouldering temperature of the tobacco rod during smoking. In a preferred embodiment, the combustion temperature of the cigarette during smoking of the cigarette is maintained at about 600xc2x0 C. to about 750xc2x0 C.
Preferably, the heat-degradable filler particles are capable of being dissipated at a temperature from about 25xc2x0 C. to about 350xc2x0 C., more preferably from about 100xc2x0 C. to about 350xc2x0 C., and most preferably from about 200xc2x0 C. to about 350xc2x0 C. In one embodiment of the invention, the heat-degradable filler particles comprise materials based on cellulose. For instance, the heat-degradable filler particles may comprise an alkyl cellulose, an ethyl cellulose, a cellulose propionate, a cellulose butyrate, a mixed ester of a cellulose, or mixtures thereof. Other suitable materials for the heat-degradable filler particles include various inorganic and polymeric materials. For example, materials such as monosodium phosphate, disodium phosphate, carnauba, polyethylene oxide, vinyl acetate, polymethacrylate, nitrocellulose, ethylene vinyl acetate, and mixtures thereof may also be used. Particularly preferred materials include ethyl cellulose, monosodium phosphate, or mixtures thereof.
In a preferred embodiment, the heat-degradable filler particles are dissipated at a distance from about 0.1 mm to about 10 mm in advance of a charline, wherein the charline is formed in the cigarette paper during smoking of the cigarette. In a more preferred embodiment, the heat-degradable filler particles are dissipated at a distance from about 0.5 mm to about 2 mm in advance of the charline. Preferably, the heat-degradable filler particles typically have a mean average particle size ranging from about one quarter the thickness of the paper to about one and a half times the thickness of the paper. For instance, in a preferred embodiment, the mean average particle size is from about 0.2 mm to about 0.5 mm in size.
A method of making a cigarette paper having heat-degradable filler particles as described above, is also provided. The method comprises adding the heat-degradable filler particles to a feedstock of a cigarette paper making machine.
A method of making a cigarette is also provided, comprising (i) providing a cut filler to a cigarette making machine to form a tobacco rod; and (ii) placing a paper wrapper around the tobacco rod to form the cigarette, wherein the cigarette paper comprises heat-degradable filler particles, and wherein said heat-degradable filler particles are capable of being dissipated during smoking of the cigarette to increase the porosity of the cigarette paper wrapper. Methods for smoking the described cigarette are also provided, comprising lighting the cigarette to form smoke and inhaling the smoke, wherein during the smoking of the cigarette, the heat-degradable filler particles are dissipated during smoking of the cigarette to increase the porosity of the cigarette paper wrapper.